<?php

function imageStyle($uri, $w = 50, $h = 50)
{
    // Get a reference to the controller object
    $CI = get_instance();

    // You may need to load the model if it hasn't been pre-loaded
    $CI->load->model('util/image_model');

    // Call a function of the model
    return $CI->image_model->image_style_url($uri, $w, $h);
}